The €149 (£126) Peak on the other hand is the more powerful device, offering a 4.3-inch qHD IPS touchscreen display, 8-megapixel rear-facing camera and 2-megapixel camera in front. The same expandable 4GB of internal storage is present, but the smartphone has a 1.2GHz Qualcomm Snapdragon S4 processor and an 1800mAh battery.

A Geeksphone spokesperson has said both handsets are currently out of stock due to great demand, but the sale of the Peak and the Keon will restart soon.

However, when we checked out the Geeksphone site, it was currently down whilst site maintenance was performed (4pm BST).

The handsets are not for general sale yet, instead aimed at developers wishing to have access to smartphones running the Mozilla Firefox OS. The new operating system works by treating HTML5 apps as native, meaning any apps built on the platform will work on any other smartphone platforms like iOS and Android.

“With early access to hardware, developers can test the capabilities of Firefox OS in a real environment with a mobile network and true hardware characteristics like the accelerometer and camera that are not easily tested on the Firefox OS Simulator,” said Stormy Peters, Mozilla’s head of developer engagement, in a blog post. “Plus, new hardware is fun to play with!”

LG and Huawei are tipped to launch Firefox OS handsets for the mainstream market, with Mozilla’s greatest aim to offer handsets that appeal to consumers in developing markets. The ZTE Open has already been confirmed as a Firefox OS handset, along with the Alcatel OneTouch Fire.